I’ve quietly resolved performance issues by re-writing slow queries to avoid
DISTINCT. Often, the
DISTINCTis there only to serve as a “join-fixer,” and I can explain what that means using an example.
I’ve seen this a lot as well, and it usually comes from people not understanding the data model or not understanding how to use subqueries (or common table expressions, the APPLY operator, etc.) to define subsets of data.